Gr Introduction; Ha Overview - Huawei NetEngine80E Configuration Manual - Reliability
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- Configuration manual - reliability (1432 pages) ,
- Configuration manual (1301 pages) ,
- Installation manual (169 pages)
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HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
6.1 GR Introduction
Defined as an extension of IP/MPLS by the IETF, GR ensures the uninterrupted forwarding
during the protocol restart, which limits the flapping of the control-plane protocols during the
AMB/SMB switchover.
6.1.1 HA Overview
The technologies that implement HA include redundancy backup, HSB, and GR.
In practical network, the network may fail and the service may be interrupted because of
inevitable non-technical factors. To improve the system availability, it is feasible to improve the
fault-tolerance capability of the system, speed up recovery from faults, and reduce the impact
of faults on the service.
High availability (HA) indicates that a device has high reliability.
Generally, Mean Time to Repair (MTTR) and Mean Time Between Failures (MTBF) are used
to assess the reliability of a device.
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The less the time is, the greater the MTTR is and the higher the device reliability is.
In the telecommunication industry, 99.999% availability means that service interruption caused
by device failures must be less than 5 minutes each year.
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AMB/SMB switchover is an important method to ensure the system availability when the system
fails.
Data may be lost during AMB/SMB switchover. Most lost data can be restored smoothly through
hot standby (HSB). The lost data that cannot be restored through HSB can be restored through
Graceful Restart (GR).
Redundancy Backup
Redundancy backup for the key components in the system is an important method to improve
the fault-tolerance capability of the system.
Redundancy backup is performed in the following modes:
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Issue 02 (2011-09-10)
MTTR: indicates the average time that a component or a device takes to recover from a
failure.
In broader sense, MTTR refers to spare part management, customer service, and is an
important index to evaluate equipment maintenance.
The formula of MTTR is as follows:
MTTR = Fault detection time + Board replacement time + System initialization time + Link
recovery time + Route coverage time + Forwarding recovery time
MTBF: indicates the average time (usually in hours) when a component or a device works
without any failure.
1+1 backup: Two components must mirror each other. If the master component is Down,
the slave component takes over the previous component to ensure that the system service
is not interrupted.
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Copyright © Huawei Technologies Co., Ltd.
6 GR Configuration
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